int a[8];
char *day[]
     ={"","MONDAY","TUESDAY","WEDNESDAY","THURSDAY","FRIDAY","SATURDAY","SUNDAY"};
main()
{
    int i,t,j;
    a[4]=6;
    for (i=1;i<=3;i++)
    {
        a[i]=2;
        if (!a[i+3]) a[i+3]=7;
        else {  a[i]=0; continue; }
        for (t=1; t<=3; t++)
        {
            if (!a[t]) a[t]=5;
            else continue;
            if (!a[t+2])a[t+2]=4;
            else {  a[t]=0;continue; }
            
            for (j=5; j<7; j++)
            {
                if (!a[j]) a[j]=3;
                else continue;
                
                if (!a[j+1]) a[j+1]=1;
                else {  a[j]=0; continue; }
                for (i=1;i<=7;i++)
                 printf("Doctor %c is on duty %s.\n",'A'+a[i]-1,day[i]);
                 exit(0);
            }
        }
    }
}